Electric utilities, manufacturing plants and industrial facilities typically burn fossil fuels like coal to produce electric power and heat for process requirements. Burning fossil fuel produces an emission stream containing a number of substances as by-products. These substances include fine particulate matter, mercury and oxides of nitrogen and sulfur. Oxides of sulfur, generally known as SOx are an environmental problem as both NOx and SOx compounds contribute to the formation of acid rain which is harmful to plant life, animal life and property.
The typical methods of reducing NOx and SOx emissions are by burning low-sulfur coal, fabric filters, the use of an electrostatic precipitator (ESP), catalytic systems or scrubbers which employ a flue gas desulfurization (FGD) apparatus. Burning low-sulfur coal reduces the particulate collection efficiency of the ESP and is much more expensive than ordinary coal. Using FGD equipment is very expensive to build and maintain.
There are a number of commercial technologies that can separately control power plant particulate and SOx emissions. Both ESP's and fabric filters are used for particulate control and either wet or dry scrubbers are used for SOx controls. The cost for both controls is moderate in terms of overall power generating costs, but both technologies require equipment that is substantial in size, and both technologies require considerable maintenance.
U.S. Pat. No. 6,302,945 B1 to Altman et al. discloses an electrostatic precipitator for removing sulfur dioxide and other polluting particles which has a wet liquid removal area or compartment downstream and in the last section of plates of the electrostatic precipitator. The precipitator uses a clear liquid scrubbing system to help remove sulfur dioxide.
U.S. Pat. No. 6,365,112 B1 to Babko-Malyi et al. discloses an improvement in an electrostatic precipitator for removing contaminates from a stream of contaminant-laden gas conducted through a conduit in the electrostatic precipitator by passing the reagent fluid through corona discharge active zones.
What is needed in the art is a process of sulfur oxide removal that is moderately priced and that can be used with existing pollution removal systems but yet achieve a high amount of sulfur removal.